Well, it will need all nodes that are required on the operation to be up, and to response in a timely fashion, even a time-out rpc of 1 replica will get you a fail response.
CL is calculated based on the RF configured for the ColumnFamily. "The ConsistencyLevel is an enum that controls both read and write behavior based on <ReplicationFactor> in your storage-conf.xml." QUORUM = RF / 2 +1; ALL = RF ONE = 1 ANY = 0 Then, on a column family configured with RF = 6, QUORUM means "be sure to write at least over 4 nodes before responding", but on a column family configured with RF = 3, QUORUM means "be sure to write on 2 at least". In cases where RF is 1 or 2, then QUORUM is like ALL ("be sure to write on all nodes involved"). On Thu, Feb 24, 2011 at 3:29 PM, mcasandra <mohitanch...@gmail.com> wrote: > > > Javier Canillas wrote: > > > > Instead, when you execute the same OP using CL QUORUM, then it means > > RF /2+1, it will try to write on the coordinator node and replica. > > Considering only 1 replica is down, the OP will success too. > > > > I am assuming even read will succeed when CL QUORUM and RF=3 and 1 node is > down. > > > Javier Canillas wrote: > > > > Now consider same OP but with CL ALL, it will fail since it cant > > assure that coordinador and both replicas are updated. > > > > Can you please explain this little more? I thought CL ALL will fail because > it needs all the nodes to be up. > http://wiki.apache.org/cassandra/API > > -- > View this message in context: > http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Understand-eventually-consistent-tp6038330p6061399.html > Sent from the cassandra-u...@incubator.apache.org mailing list archive at > Nabble.com. >